fontforge/designwithfontforge.com — pull request #56 by royblumenthal (2014-11-11 19:46:40+00:00)
Title: Update Using_the_Fontforge_Drawing_Tools.md

The possessive of "OS" is "OS's", not "OS'". The apostrophe-s is essential. The new 'norm' that's emerging is grammatically incorrect, and a rather poor (and modern) Americanisation.